The Dyeing of Cellulose with Direct Dyes

The Influence of Different Electrolytes on the Interaction of Chlorazol Sky Blue FF with the Cotton Fiber Surface in Aqueous Solutions

“…The constancy of the affinity values leads to the conclusion that the nature of the adsorption process and the driving force involved therein are independent of the nature of the alkali metal cation used. All these results mentioned above provide further strong support to the modifications introduced [28,29] in the current theory of dyeing of cellulosic fibers by direct dyes.…”

“…Extensive investigations by the present authors and coworkers have recently been carried out on the dyeing of cellulose with direct dyes -Chlorazol Sky Blue wiff [28,29] and Chrysophenine G. It was shown &dquo; that the dye adsorption isotherms ~ould be satisfactorily explained on the basis of the current electrochemical theories of dyeing [8,16,24,31 if suitable modifications were introduced in the theory. These modifications relate to the use.…”

“…The iso-, therms obtained at 60°C (not shown here) are similar to those given in Figure 1 and are consistent with the exothermic nature of the adsorption process. These experimental adsorption isotherms have been analyzed on the basis of a model for the celluloseaqueous direct dye + electrolyte solution system, which had been previously put forward [28,29]. It was shown earlier [28J, from an analysis of several equilibrium adsorption isotherms for the direct dyes Chlorazol Sky Blue F~F and Chrysophenine G on cotton, viscose and cuprammonium rayon fibers, that the equilibrium adsorption data could be explained satisfactorily on the basis of this proposed model.…”

“…Furthermore, the contribution to the total surface charge of ionized carboxyls' present in cellulose is always taken into account when calculating the Donnan distribution of ions at the celluloseaqueous direct dye + electrolyte solution interface. It has been shown earlier [28,29] that the equilibrium existing between the dye ions present in the internal solution phase i and the dye ions adsorbed on the cellulose phase v could be described by the following Langmuir-type equation…”